Figure 7.

Pontine reticular nucleus, oral part (PnO) microinjection of 3-mercaptopropionic acid (3-MPA) significantly (*) and reversibly increased sleep and decreased wakefulness. Microinjection of 3-MPA decreased wakefulness by 29% (A), increased non-rapid eye movement (NREM) sleep by 68% (B), and increased rapid eye movement (REM) sleep by 193% (C) during the first hour after PnO microinjection. Although the effects did not reach statistical significance, 3-MPA showed a trend toward decreasing the latency to onset of NREM sleep and REM sleep (D) by 42% and 29%, respectively. During the first hour, an increase in the number of episodes of wakefulness (E, 28%), NREM sleep (F, 31%), and REM sleep (G, 190%) was also observed after 3-MPA microinjection, but only the increase in the number of NREM sleep and REM sleep episodes achieved statistical significance. 3-MPA microinjection sites (H) were localized to the PnO and are indicated by filled circles on 3 coronal diagrams modified from a rat brain atlas.³⁹ Numbers at the right of each diagram indicate mm posterior to bregma. The PnO sites where 3-MPA was microinjected extended from −7.97 to −8.51 mm from bregma.